Two in one!
At 1:50 +0200 2003/02/07, Vadim Vygonets wrote:
>[revised]
>
>Quoth Giuliano Gavazzi on Thu, Feb 06, 2003:
>> well, it would probably be more correct to say that (the host)
>> bar.my.dom. is the only mail exchanger for the domain of the same
>> name..
>
>This is the correct terminology, indeed. But host names are also
>domain names, so a host pointed to by the domain name bar.my.dom
>is the MX record for itself's domain.
>
>> this is why MX records should never be omitted, the left and
>> right hand side are never the same thing.
>> This is in RFC 7821.
>
>Where does RFC 2821 say you shouldn't omit MX records? It
>clearly states that an omitted MX record is an implicit MX record
>of priority 0 pointing to itself.
did I mention 2821? No. Also I was referring to the LHS and RHS, not
to the MX. Maybe I should have put one of those silly smileys and the
spirit would have been clearer...
>And what do you mean by them not being the same thing? Consider:
>
>foo IN MX 10 foo
>foo IN A 1.2.3.4
>
>The A record gets looked up whether the MX record exists or not,
>and for the same reason. So how is the name on the LHS different
>from the one on the RHS?
let me take my argument further: if you have an MX you are clearly
stating that the mail for domain foo is dealt with by host foomx
(your example is misguiding, using foo twice). There might not exist
an host foo at all. While if you only have an A record for foo and no
MX at all, you are saying that mail for host foo is dealt by foo
itself. Host foo exists necessarily in this case.
At 4:18 +0200 2003/02/07, Vadim Vygonets wrote:
>Quoth Greg A. Woods on Thu, Feb 06, 2003:
[...]
> > "Ya know.... " there's a reason why people use unique names with
>> prefixes like "mail" and "www" for different services... :-)
>
>Hmm, no, I don't really see one, except convenience. Also, 'ftp'
>and 'www' are often CNAME records.
>
because one day you might want to split those services amongst
distinct hosts (to spread the load/rationalise the organisation), but
you've got everyone used to a single name and you are stuck!
Giuliano
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